jetting question

[elliottles1]

Hi folks,

i have a DT400 full recon engine, sweet as a nut, with a pwk 34mm carb (new) and to start with, standard size jetting.
question is, the bike refused to rev thru a midrange splutter, so i lowered the needle (clip now on the top setting) and it is greatly improved but not gone completely. so where do i go from here?? smaller idle jet? or smaller main jet?

any ideas welcomed.

cheers
les

[1976RD400C]

I think you may have to research the needles for that carb and find one that will make it leaner.

[m in sc]

yup. leaner needle. also depends where on the needle you need to lean it out. refer to chart.


https://www.keihin-na.com/assets/1/7/pwk-pj_jetneedles.pdf

[Alain2]

As a temporary fix you could put a smaller pilot if you have one available, it could help lean 1/4 throttle just enough to make it rev.

[elliottles1]

alain,

i think you are right, i have fitted the widest needle in a 10 needle set and it is still slightly too rich coming off tickover although it now goes thru it and flies. i think the pilot jet is too large and is making the problem worse. i am waiting on some smaller pilot  jets but the problem is basically solved. thanks to all. really enjoying buzzing up and down the road running it in.
it would pull a stump out.
cheers
les